The present invention relates to a hydraulic aggregate with at least one displacement machine, in particular a radial piston machine such as a pump or motor.
All displacement machines, such as hydraulic pumps and motors operate in accordance with the displacement principle. A fluid is supplied at an inlet side into an increasing displacement chamber, the chamber is closed, then it is connected with a discharge side and the fluid is discharged from the reducing displacement chamber. The displacement machines operate in accordance with a rotary displacement principle and a rectilinear displacement principle. Rotary displacement machines provide feeding in cells, whose volume cyclically changes by the geometric design of the limiting walls, such as for example gear machines, screw machines, vane cell machines, etc. The rectilinear displacement machines change the cell volumes by a reciprocating movement of a piston in a cylinder, for example axial piston machines, radial piston machines, etc.
Radial piston machines, such as pumps or motors, have a driving mechanism with a cylinder-piston unit and an adjusting element acting on the piston. The pistons as a rule are radially displaceably guided in a cylinder star. The adjusting element can be formed for example as a lifting ring or an eccentric, which can be arranged radially inside the piston or radially outside the piston. Basically the adjustment elements of the cylinder stars can be rotatable.
A driving/driven shaft is operatively connected with the rotating part of the driving mechanism. In a pump it transmits a torque from outside inwardly to the driving mechanism, and in a motor it transmits a torque from the driving mechanism outwardly. The driving/driven shaft of the radial piston machine extends as a rule outwardly through a cover and is supported in the cover and/or the housing of the radial piston machine. For compensating an axial and/or radial offset between the driving mechanism and the shaft, it is known to provide a compensating coupling between the driving mechanism and the shaft.
A component of a machine unit is connected with the free end of the driving/driven shaft of the radial piston machine. In particular, it was a shaft, or also it can be a toothed gear. The machine unit as a rule is formed in a radial piston pump by a motor, and in a radial piston motor it is formed by a consumer or a generator.
For compensating a radial and an axial offset between the driving/driven shaft of the radial piston machine and the component of the machine unit, it is known to arrange a second compensating coupling between the component and the driving/driven shaft.
Furthermore, the European patent document EP 0886 067 A1 discloses a hydraulic aggregate with a drive unit and a pump unit. The drive unit and the pump unit are flanged over one another. An input shaft of the pump unit operates as a centering element for a drive shaft of the drive unit. The drive shaft is connected directly form-lockingly with the input shaft of the pump unit and supported by bearing points of the input shaft and through a further bearing in the housing of the drive unit.
Accordingly, it is an object of present invention to provide a hydraulic aggregate with at least one displacing machine, which avoids the disadvantages of the prior art.
More particularly, it is an object of present invention to provide a hydraulic aggregate with at least one displacement machine, in particular a radial piston machine such as a pump or a motor, which has a drive mechanism and a driving/driven shaft connected to it via a compensation coupling, and at least one machine unit which is connected operatively through a component with the driving/driven shaft of the displacement machine.ion.
It is proposed that the compensating coupling between the driving mechanism and the driving/driven shaft of the displacement machine compensates a radial and/or axial offset between the displacement machine and the machine unit. An additional compensating coupling between the driving/driven shaft and the component of the machine unit can be dispensed with and the structural length, the mounting expenses and the cost can be reduced.
A required freedom degree of the driving/driven shaft is advantageously provided since a bearing of the driving/driven shaft is eliminated, it is fixedly connected with the component of the machine unit, and it is supported by bearing points of the component. Additional components, such as for example a bearing and a bearing cover, are eliminated, an overdimensioned bearing as well as undeterminable forces on the displacement machine or on the driving mechanism can be avoided, and advantageously standard machine units can be utilized. The machine unit can be formed, for example, as a standard electric motor whose drive shaft is supported in two bearings in a statistically determined manner and fixedly connected with a drive shaft of the displacement machine. The machine unit can be produced independently from the displacement machine and can be tested for its operation.
The component of the machine unit connected with the driving/driven shaft of the displacement machine is very often formed as a shaft, for example a drive shaft in an electric motor, as an input shaft in a consumer or a generator, etc. Further, it can be formed as a toothed gear or another, suitable component. An especially simple and fast connection between the driving/driven shaft of the displacement machine and a shaft of the machine, and a shaft of the machine unit can be provided with a driving/driven shaft of the displacement machine formed as a hollow shaft, which can be mounted on the shaft of the machine unit. Furthermore, a hollow shaft can be adjusted to standard shafts of the machine units in an especially cost-favorable manner.
The driving/driven shaft and the component of the machine unit can be formed of one piece. For example, a driving shaft on an electric motor or an input shaft of a generator can be connected directly with the driving mechanism of the displacement machine through the compensating coupling. Additional components, structural length, mounting expenses and cost can be spared.
Instead of completely eliminating a bearing of the driving/driven shaft, it can be advantageous to support it in a housing part through a pendulum bearing. This bearing, together with a compensating coupling, can compensate for alignment errors, such as for example a radial offset, end running deviations, etc. The displacement machine can be connected with standard machines in an advantageous manner, such as with conventional motor shafts or standard electric motors which have no bearing on the driven shaft. An oversized bearing can be advantageously avoided. The pendulum bearing can be formed as a pendulum ball bearing or a pendulum roller bearing.
Various devices which are known for those skilled in the art can be used as a compensating coupling. It is especially advantageous when the compensation coupling is formed as a cross disk coupling. The cross disk coupling is especially short, it can compensate radial and axial gaps, and is frequently provided in a standard fashion between the driving mechanism and the driving/driven shaft of the displacing machine, in particular radial piston machines. A new construction can be avoided, and for the displacement machine technically effective and cost favorable standard structural groups can be utilized.
A part of the compensation coupling can be mounted on the driving/driven shaft. Also, a part of the compensation coupling can be preferably formed on the driving/driven shaft with one piece with it, for example with a so-called loop of a cross disk coupling, and guided in a cross slider of the cross disk coupling.
In accordance with one embodiment of the present invention it is suggested that the displacement machine and the machine unit are connected with one another through a separate intermediate housing. Separate intermediate housing can be adjusted in an especially flexible and cost favorable manner to different machine units. Thereby a displacement machine or a housing of a structural row, for example radial piston pumps with different feeding volumes, can be mounted on different machine types via the intermediate housing in an especially flexible and cost favorable manner. For example, they can be mounted on electric motors with different powers and/or different dimensions. Basically, the intermediate housing can be also formed of one piece with the housing of the displacement machine or the housing of the machine unit.
In accordance with another embodiment of the present invention, the intermediate housing of the displacement machine is sealed from outside. An additional cover of the displacement machine is therefore eliminated.
The displacement machine can be sealed in direction of the machine unit through a wall of the machine unit and possibly through a special shaft seal of a shaft of the machine unit. It is especially advantageous however when the displacement machine is sealed by a sealing on the driving/driven shaft of the displacement machine in direction of the machine unit. A special sealing of the machine unit therefore can be avoided, and the machine unit can be formed as a cost favorable standard component. Furthermore, the displacement machine can form a close unit with the intermediate housing sealing the driving/driven shaft, which can be separately manufactured and tested for its operation.
Since in accordance with the present invention the compensation of coupling between the driving mechanism and the driving/driven shaft can be used for an offset compensation between the displacement machine and the machine unit, a required freedom is provided for uncoupling the displacement machine and the machine unit with respect to the body sound. This can be achieved by a damping element, which for example is arranged between the intermediate housing and a housing of the machine unit. It is especially advantageous however when the damping element is formed of one piece with the intermediate housing. Thereby additional components, structural length and mounting expenses can be saved. This can be achieved for example with intermediate housing which is composed of vibration-dampening plastic or metal.
The inventive solution can be utilized for different hydraulic aggregates. It is especially advantageous for radial piston machines, in which frequently the driving mechanism and the driving/driven unit are separate and are connected with a compensation coupling.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.